Aim A discussion of how the construct of compassion fatigue is understood in nursing. Background Compassion fatigue is a topic commonly found in nursing literature. Design Discussion paper. Data sources The literature from 1992–2012 on compassion fatigue was examined. The literature from 1998–2012 on compassion was examined. Implications for nursing There are multiple and diverse understandings and definitions of what compassion fatigue is. So much so, there are equally multiple, diverse and conflicting strategies to mitigate it. To understand better what compassion fatigue is, an examination of what compassion is was undertaken. Much is written that nurses are, or should be compassionate. Compassion is an archetype of nursing. However, there is little in the nursing literature defining what compassion is. Literature on compassion outside of nursing was then examined. There is a growing body of theory and research about compassion in other disciplines. None of the multiple definitions of nurse compassion fatigue match this understanding of compassion. The tools most often used to measure nurse compassion fatigue do not appear to measure the construct of compassion. Conclusion To understand what nurse compassion fatigue is, we must first understand what nurse compassion is.